"Of course we have information about the detention of Russian national Makarenko," he said. Our embassy is closely monitoring the situation, we have requested consular access," Ryabkov added.

"Unfortunately, once again the American side failed to timely notify us about the detention of a Russian national in violation of the convention on consular relations," he added.

Moscow will seek to see that all rights of Russian national Dmitry Makarenko be respected, Ryabkov said. "Of course we will seek to see that all rights of our detained fellow citizen be fully ensured," he stressed.

The senior diplomat also urged Russian nationals traveling abroad to exercise caution in order not not to find themselves in a similar situation in conditions when the US authorities continue a hunt for Russian nationals.

"We urge all fellow citizens who may have grounds to believe that US law enforcement agencies could have have an issue with them, to weigh up the consequences of trips abroad, as there are no safe places, in fact, no guarantees," he stressed.

"We continue seeing a chain of episodes, incidents in which Russian nationals are detained in third countries at US requests, and then they are extradited to the US even if there is no basis for such actions. That is why it is necessary to be cautious," he said.

Makarenko was detained on Saipan on December 29 at the request of the FBI on charges of attempts to export military equipment to Russia from the US. Later he was convoyed to Florida.

An indictment was brought in by a Florida court on June 15, 2017. He is accused of a plot with an aim to attempt to illegally export to Russia military night vision equipment and thermal imagery devices, as well as of money laundering.